A single array, interlace, ink jet nozzle system is taught in U.S. Pat. No. 4,069,486 entitled "Single Array Ink Jet Printer" and issued on Jan. 17, 1978, to S. J. Fox. This patent teaches the criteria for printing an interlace pattern with a single array of ink jet nozzles. Interlace pattern printing may be defined as printing adjacent lines, each line being one picture element (pel) wide, with print nozzles that are spaced more than one pel apart on the array.
To print interlace more than one pass of the print head across the media is required. Further to prevent overprinting of one line on top of another, the Fox patent teaches that the nozzles must be uniformly spaced k pels apart on the array and that the array must translate Nt pels perpendicular to the pass direction during each print pass. Nt is the number of nozzles on the array. Further, the Fox patent teaches that k and Nt must be integers and not have any common factors.
Mr. S. J. Fox and Mr. V. C. Martin, the present inventor, working together realized that multiple arrays of uniformly spaced ink jet nozzles could also be designed to print interlace patterns. The criteria for that design is taught in U.S. Pat. No. 4,063,254 entitled "Multiple Array Printer" issued on Dec. 13, 1977.
In applying interlace printers to communication print terminals, it became desirable to print more than one resolution, pels per inch or cm. Mr. Martin, in addressing this problem, invented a multiple array variable resolution printer which is the subject of U.S. Pat. No. 4,097,873 issued on June 27, 1978, and entitled "Ink Jet Printer For Selectively Printing Different Resolutions."
While this latter invention works very well, it does require more than one array to achieve the goal of variable resolution printing with a plurality of nozzles. Of course, the apparatus taught therein could be reduced to using a single nozzle on one array to perform variable resolution printing. However, this is not desirable because of the slow speed of such a printer and the wasteful and costly nature of building multiple arrays with multiple nozzles and then using only one nozzle for resolutions other than the standard resolution. From a system cost and optimum efficiency viewpoint, it would be most desirable to have an interlace ink jet printer having multiple nozzles on one array and being able to use substantially all the nozzles to print various resolutions.